This invention relates broadly to the art of brush making, and, more particularly to machines for rounding the tips of individual brush bristles.
Prior-art patents which relate to this invention include U.S. Pat. Nos. 2,854,797 to Clief, 3,063,204 to Baumgartner, 3,355,839 to Clemens, 3,384,418 to Guey et al., and 3,451,173 to Hazelton.
Hazelton describes a machine for finishing paint brushes. In this respect, Hazelton's machine is not concerned with rounding individual brush bristles, but rather forming the overall tapered or chiseled configuration on a paint brush. In this respect, the machine continuously feeds brushes 16 below large abrasive members, or sanding discs 37. The discs are driven to rotate in the same direction and are rather large in order to produce flat but tapered shapes at the ends of brushes. Such a machine is not satisfactory for merely rounding the tips of individual bristles since it changes the contour of the overall brush. Thus, it is an object of this invention to provide a brush bristle roundator which rounds, or dulls, the tips of individual bristles, and which maintain an existing overall brush contour.
Clief and Clemens, on the other hand, describe machines for rounding the tips of bristles which have not yet been mounted in brush backs. That is, the bristles are maintained in tufts during the rounding process. These machines are not totally satisfactory in that they require a rather complicated structure for holding the tufts while they are being rounded. Further, they are relatively slow in operation since the bristle tips of each tuft must be individually processed. Thus, it is an object of this invention to provide a brush bristle roundator which is relatively uncomplicated in structure and which can be used to round the bristles of entire brushes at one time.
In Guey et al. and Baumgartner the bristle tips of brushes are held against grinding discs. In Baumgartner the discs are not only rotated but are moved in an eccentric circular path to properly flex the brush bristles. Each successive disc is rotated in an opposite direction. The brushes are carried by a wheel over the centers of the circular paths of the discs. A difficulty with this system is that the complex motions of the discs are jerky in operation, therefore leading to a short lifetime of the overall apparatus. Further, this system, as well as the system of Guey et al., cannot be readily used for brushes whose outer shapes are contoured, such as rounded. Thus, it is an object of this invention to provide a brush roundator that is smooth in operation and which can be used with contoured brushes.
Some prior-art brush roundators have employed brush holders which repeatedly rotate brushes held thereby about axes at brush backs thereof while the bristles thereof are in contact with an abrading disc. Although such a machine can be used for roundating contoured brushes, it is slow in operation and not generally suited for production line manufacturing. Thus, it is an object of this invention to provide a brush roundator which is not only suitable for contoured brushes but also allows high speed production.